The present invention relates to a carburetor for a motor vehicle engine and more particularly to a system for preventing the percolation of fuel to the induction passage of the carburetor.
When an engine operation is stopped after the driving of a motor vehicle at a high atmospheric temperature, the engine room reaches a high temperature which causes the elevation of temperature of fuel in the carburetor. The pressure of generated fuel vapor causes the percolation of fuel to the induction passage through air-fuel mixture passages and a float chamber vent passage. Consequently, air-fuel mixture is extremely enriched at re-starting of the engine, which deteriorates starting ability and driveability after starting.
In order to prevent the percolation of fuel, there has been proposed various measures, such as the cooling of the carburetor by a fan, insulating the carburetor by thermal insulation, and others. However, these methods are not effective on preventing of percolation, since heat capacity of the carburetor is large.